Performance of an Isobaric Hybrid Compressed Air Energy Storage System at Minimum Entropy Generation

Sammy Houssainy, Mohammad Janbozorgi, Pirouz Kavehpour

Research output: Contribution to journalArticlepeer-review

8 Scopus Citations


Efficient, large-scale, and cost-effective energy storage systems provide a means of managing the inherent intermittency of renewable energy sources and drastically increasing their utilization. Compressed air energy storage (CAES) and its derivative architectures have received much attention as a viable solution; however, optimization objectives for these systems have not been thoroughly investigated in the literature. A hybrid thermal and compressed air energy storage (HT-CAES) system is investigated that mitigates the shortcomings of the otherwise attractive conventional CAES systems and its derivatives—shortcomings such as strict geological locations, low energy densities, and the production of greenhouse gas emissions. The HT-CAES system allows a portion of the available energy to operate a compressor and the remainder to be converted and stored in the form of heat through joule/resistive heating in a high-temperature, sensible, thermal energy storage medium. Internally reversible and irreversible HT-CAES system assumptions were investigated, in addition to regenerative and non-regenerative design configurations. Several system optimization criteria were examined—including maximum energy efficiency, maximum exergy efficiency, maximum work output, and minimum entropy generation—with a focus on whether the latter may lead to conclusive design guidelines in a real system. It is shown that an HT-CAES system designed based on a minimum entropy generation objective may operate at a lower energy and exergy efficiency as well as lower output power than otherwise achievable. Furthermore, optimization objective equivalence is shown to be limited to certain design conditions.

Original languageAmerican English
Article numberArticle No. 052001
Number of pages9
JournalJournal of Energy Resources Technology, Transactions of the ASME
Issue number5
StatePublished - May 2020

Bibliographical note

Publisher Copyright:
Copyright © 2020 by ASME.

NREL Publication Number

  • NREL/JA-5500-75543


  • Alternative energy sources
  • CAES
  • Compressed air energy storage
  • Energy conversion/systems
  • Energy storage
  • Energy storage systems
  • Energy systems analysis
  • Heat energy generation/storage/transfer
  • Hybrid energy storage
  • Minimum entropy generation
  • Renewable energy
  • Thermal energy storage


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